Nicknames considered harmful
The practice of using silly nicknames or "handles" in social software was inherited, I think, from the CB radio fad of the 1970's. Radio operators didn't want to use their real names, especially when the purpose of the radio was often to evade local traffic enforcement efforts. Distinctive monikers are easier to remember than cryptic call signs.
This was fine for helping truckers avoid Smoky, but it is pernicious in weblog comments and forums. Names remind everyone that they are addressing people, not hunting scalps in some sort of a silly game. And names remind us that people have real expertise, real work, and real accomplishments — though some of them, to be sure, sit in bed all day and troll the net looking for a good fight.
It's easy to assume that Parkaboy is an idiotic kid or a sockpuppet. It's just as likely that he's a distinguished professor or an insightful professional. We are used to knowing people, and to being reminded that people are people; handles make people less human and discourse less humane.
Some people worry about privacy. But, if you're making a public statement, it's a public statement; if you're not willing to be responsible for your words, I think you generally should hold your peace. Exceptions need to be made, of course, for people who have important things to say, things we need to hear but which they dare not say without protection; in these special circumstances, a shield of anonymity makes sense.